The method of developing a latent image formed on a photoconductive surface by means of electrophoretic transfer of liquid toner is well known in the art. In this method, charged particles suspended in a non-polar insulating carrier liquid migrate under the influence of an electrostatic field and concentrate in image forming configuration upon relatively charged or discharged areas of a photoconductive surface. The latent image so developed is then transferred to a substrate, such as paper, either directly or by means of one or more intermediate transfer members.
In U.S. Pat. No. 4,504,138 a different method for the developing of a latent image is described. The method described involves applying a thin viscous high density layer of toner particles on the circumferential surface of a roller and bringing the layer so formed to the photoconductive surface. Transfer of selected portions of the toner layer onto the photoconductive surface then occurs as a function of the electric field strength of the latent image.
In Canadian Patent 990589, a method of developing electrostatic images is described which involves producing a film of liquid toner on a first applicator and bringing the applicator in contact with the final substrate which carries a latent image, thereby to develop the image. A second applicator bearing a layer of carrier liquid is then brought into contact with the substrate to remove background deposits and to squeegee out excess liquid. The film of liquid toner described in Canadian Patent 990589 has between 2-4 per cent of toner concentrate dispersed within the carrier liquid.